Tokyo Electron Limited

Etsuo Iijima

Norikazu Yamada

Akiteru Koh

Hiroshi Tsuchiya

Meiki Koh

A main etching step is effected in a state shown in FIG.A under a first pressure using a gas containing at least HBr, e.g., a mixture gas of HBr and Clas an etching gas. The main etching is ended before a silicon oxide film, as shown in FIG.B, is exposed. An over-etching process is effected under a second pressure higher than the first pressure using a gas containing at least HBr, e.g., an HBr single gas so as to completely expose the silicon oxide filmas shown in FIG.C. In such a way, the selectivity of a silicon-containing conductive layer with respect to the silicon oxide film is improved compared to conventional methods. Without etching the silicon oxide film layer, which is an underlying layer, and without marring the shape of the silicon-containing conductive film layer formed by etching, only the desired silicon-containing conductive film layer is removed by etching reliably.

Dry-etching method

A dry-etching method using an apparatus where a wafer is placed on either of a pair of opposed electrodes provided in an etching chamber, and high-frequency power is supplied to both the opposed electrodes to effect a plasma etching. The plasma etching uses a gas containing at least Cland HBr. Trenchesare formed, as shown in FIG.B, in a silicon wafershown in FIG.A through a mask layer such as a nitride silicon layer. While adjusting the high-frequency power supplied to the opposed electrode where the wafer is placed, the shape of the sidewallsof the trenchesis controlled. Thus, the trenches can have desired shapes even if the widths of the trenches are different.

An RF power (Bottom RF) from a radio-frequency power sourceis turned off (t) and the supply of a He gasto a back face of a wafer W is stopped (t) when an end point detector(EPD) detects an end point (t), and a high-voltage DC power source(HV) is turned off (t) under the condition in which an RF power (Top RF) from a radio-frequency power sourceis controlled to fall within a range in which etching does not progress and plasma discharge can be maintained (t). This process enables the inhibition of the adhesion of particles while an etching amount is accurately controlled.

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Nirasaki, Japan

Etsuo Iijima